added label syntax support and highlighting

lyng-idea/src/main/kotlin/net/sergeych/lyng/idea/annotators/LyngExternalAnnotator.kt

@@ -94,6 +94,16 @@ class LyngExternalAnnotator : ExternalAnnotator<LyngExternalAnnotator.Input, Lyn
 
         val out = ArrayList<Span>(256)
 
+        fun isFollowedByParenOrBlock(rangeEnd: Int): Boolean {
+            var i = rangeEnd
+            while (i < text.length) {
+                val ch = text[i]
+                if (ch == ' ' || ch == '\t' || ch == '\r' || ch == '\n') { i++; continue }
+                return ch == '(' || ch == '{'
+            }
+            return false
+        }
+
         fun putRange(start: Int, end: Int, key: com.intellij.openapi.editor.colors.TextAttributesKey) {
             if (start in 0..end && end <= text.length && start < end) out += Span(start, end, key)
         }
@@ -207,16 +217,6 @@ class LyngExternalAnnotator : ExternalAnnotator<LyngExternalAnnotator.Input, Lyn
 
             val tokens = try { SimpleLyngHighlighter().highlight(text) } catch (_: Throwable) { emptyList() }
 
-            fun isFollowedByParenOrBlock(rangeEnd: Int): Boolean {
-                var i = rangeEnd
-                while (i < text.length) {
-                    val ch = text[i]
-                    if (ch == ' ' || ch == '\t' || ch == '\r' || ch == '\n') { i++; continue }
-                    return ch == '(' || ch == '{'
-                }
-                return false
-            }
-
             // Build simple name -> role map for top-level vals/vars and parameters
             val nameRole = HashMap<String, com.intellij.openapi.editor.colors.TextAttributesKey>(8)
             for (d in mini.declarations) when (d) {
@@ -253,7 +253,7 @@ class LyngExternalAnnotator : ExternalAnnotator<LyngExternalAnnotator.Input, Lyn
             if (e is com.intellij.openapi.progress.ProcessCanceledException) throw e
         }
 
-        // Add annotation coloring using token highlighter (treat @Label as annotation)
+        // Add annotation/label coloring using token highlighter
         run {
             val tokens = try { SimpleLyngHighlighter().highlight(text) } catch (_: Throwable) { emptyList() }
             for (s in tokens) if (s.kind == HighlightKind.Label) {
@@ -261,8 +261,29 @@ class LyngExternalAnnotator : ExternalAnnotator<LyngExternalAnnotator.Input, Lyn
                 val end = s.range.endExclusive
                 if (start in 0..end && end <= text.length && start < end) {
                     val lexeme = try { text.substring(start, end) } catch (_: Throwable) { null }
-                    if (lexeme != null && lexeme.startsWith("@")) {
-                        putRange(start, end, LyngHighlighterColors.ANNOTATION)
+                    if (lexeme != null) {
+                        // Heuristic: if it starts with @ and follows a control keyword, it's likely a label
+                        // Otherwise if it starts with @ it's an annotation.
+                        // If it ends with @ it's a loop label.
+                        when {
+                            lexeme.endsWith("@") -> putRange(start, end, LyngHighlighterColors.LABEL)
+                            lexeme.startsWith("@") -> {
+                                // Try to see if it's an exit label
+                                val prevNonWs = prevNonWs(text, start)
+                                val prevWord = if (prevNonWs >= 0) {
+                                    var wEnd = prevNonWs + 1
+                                    var wStart = prevNonWs
+                                    while (wStart > 0 && text[wStart - 1].isLetter()) wStart--
+                                    text.substring(wStart, wEnd)
+                                } else null
+                                
+                                if (prevWord in setOf("return", "break", "continue") || isFollowedByParenOrBlock(end)) {
+                                    putRange(start, end, LyngHighlighterColors.LABEL)
+                                } else {
+                                    putRange(start, end, LyngHighlighterColors.ANNOTATION)
+                                }
+                            }
+                        }
                     }
                 }
             }
@@ -364,6 +385,16 @@ class LyngExternalAnnotator : ExternalAnnotator<LyngExternalAnnotator.Input, Lyn
         private val CACHE_KEY: Key<Result> = Key.create("LYNG_SEMANTIC_CACHE")
     }
 
+    private fun prevNonWs(text: String, idxExclusive: Int): Int {
+        var i = idxExclusive - 1
+        while (i >= 0) {
+            val ch = text[i]
+            if (ch != ' ' && ch != '\t' && ch != '\n' && ch != '\r') return i
+            i--
+        }
+        return -1
+    }
+
     /**
      * Make the error highlight a bit wider than a single character so it is easier to see and click.
      * Strategy:

lyng-idea/src/main/kotlin/net/sergeych/lyng/idea/highlight/LyngColorSettingsPage.kt

@@ -43,10 +43,15 @@ class LyngColorSettingsPage : ColorSettingsPage {
         }
         
         var counter = 0
-        counter = counter + 1
+        outer@ while (counter < 10) {
+          if (counter == 5) return@outer
+          counter = counter + 1
+        }
     """.trimIndent()
 
-    override fun getAdditionalHighlightingTagToDescriptorMap(): MutableMap<String, TextAttributesKey>? = null
+    override fun getAdditionalHighlightingTagToDescriptorMap(): MutableMap<String, TextAttributesKey> = mutableMapOf(
+        "label" to LyngHighlighterColors.LABEL
+    )
 
     override fun getAttributeDescriptors(): Array<AttributesDescriptor> = arrayOf(
         AttributesDescriptor("Keyword", LyngHighlighterColors.KEYWORD),
@@ -58,6 +63,7 @@ class LyngColorSettingsPage : ColorSettingsPage {
         AttributesDescriptor("Punctuation", LyngHighlighterColors.PUNCT),
         // Semantic
         AttributesDescriptor("Annotation (semantic)", LyngHighlighterColors.ANNOTATION),
+        AttributesDescriptor("Label (semantic)", LyngHighlighterColors.LABEL),
         AttributesDescriptor("Variable (semantic)", LyngHighlighterColors.VARIABLE),
         AttributesDescriptor("Value (semantic)", LyngHighlighterColors.VALUE),
         AttributesDescriptor("Function (semantic)", LyngHighlighterColors.FUNCTION),

lyng-idea/src/main/kotlin/net/sergeych/lyng/idea/highlight/LyngHighlighterColors.kt

@@ -82,4 +82,9 @@ object LyngHighlighterColors {
     val ENUM_CONSTANT: TextAttributesKey = TextAttributesKey.createTextAttributesKey(
         "LYNG_ENUM_CONSTANT", DefaultLanguageHighlighterColors.STATIC_FIELD
     )
+
+    // Labels (label@ or @label used as exit target)
+    val LABEL: TextAttributesKey = TextAttributesKey.createTextAttributesKey(
+        "LYNG_LABEL", DefaultLanguageHighlighterColors.LABEL
+    )
 }

lyng-idea/src/main/kotlin/net/sergeych/lyng/idea/highlight/LyngLexer.kt

@@ -133,10 +133,24 @@ class LyngLexer : LexerBase() {
             return
         }
 
-        // Identifier / keyword
+        // Labels / Annotations: @label or label@
+        if (ch == '@') {
+            i++
+            while (i < endOffset && (buffer[i].isIdentifierPart())) i++
+            myTokenEnd = i
+            myTokenType = LyngTokenTypes.LABEL
+            return
+        }
+
         if (ch.isIdentifierStart()) {
             i++
             while (i < endOffset && buffer[i].isIdentifierPart()) i++
+            if (i < endOffset && buffer[i] == '@') {
+                i++
+                myTokenEnd = i
+                myTokenType = LyngTokenTypes.LABEL
+                return
+            }
             myTokenEnd = i
             val text = buffer.subSequence(myTokenStart, myTokenEnd).toString()
             myTokenType = if (text in keywords) LyngTokenTypes.KEYWORD else LyngTokenTypes.IDENTIFIER

lyng-idea/src/main/kotlin/net/sergeych/lyng/idea/highlight/LyngSyntaxHighlighter.kt

@@ -33,6 +33,7 @@ class LyngSyntaxHighlighter : SyntaxHighlighter {
         LyngTokenTypes.BLOCK_COMMENT -> pack(LyngHighlighterColors.BLOCK_COMMENT)
         LyngTokenTypes.PUNCT -> pack(LyngHighlighterColors.PUNCT)
         LyngTokenTypes.IDENTIFIER -> pack(LyngHighlighterColors.IDENTIFIER)
+        LyngTokenTypes.LABEL -> pack(LyngHighlighterColors.LABEL)
         else -> emptyArray()
     }
 

lyng-idea/src/main/kotlin/net/sergeych/lyng/idea/highlight/LyngTokenTypes.kt

@@ -29,6 +29,7 @@ object LyngTokenTypes {
     val NUMBER = LyngTokenType("NUMBER")
     val KEYWORD = LyngTokenType("KEYWORD")
     val IDENTIFIER = LyngTokenType("IDENTIFIER")
+    val LABEL = LyngTokenType("LABEL")
     val PUNCT = LyngTokenType("PUNCT")
     val BAD_CHAR = LyngTokenType("BAD_CHAR")
 }